<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="btn">+1</button>
    <script>
        const dom = document.getElementById('btn')
        // dom.addEventListener('click',function(){
        //     console.log(this,'this')
        // })
        dom.attachEvent('onclick',function(){
            console.log(this,'this1')
        })
    </script>
</body>
</html>